Make before break magnetically-operated reed-type contact



June 8, 1965 G, wEssEL 3,188,426

MAKE BEFORE BREAK MAGNETICALLY-OPERATED REED-TYPE CONTACT INVENTOR G. WE SS EL @bhw June s, 1965 G. wEssl-:L 3,188,426

MAKE BEFORE BREAK MAGNETICALLY-OPERATED REED-TYPE CONTACT Filed Nov. 2, 1962 2 Sheets-Sheet 2 zw. e' \"\\\w 8 3 3 o b c d e F ig.3

INVENTOR. G.wEssEz Bwumwf/J United States Patent O 3,188,426 MAKE BEFORE BREAK MAGNETICALLY- PERATED REED-TYPE CNTACT Gerhard Wessel, Kornwestheim, Wurtternberg, Germany, assignor t International Standard Electric Corporation, New York, NY., a corporation of Delaware Filed Nov. 2, 1962, Ser. No. 234,960 Claims priority, application Germany, Nov. 22, 1961,

1 Claim. (Cl. 260-87) 'Ilhe invention relates to magnetically operated reedtype switchover contacts in which the resting position of the contact remains closed Iuntil after contact is made in the operated position.

Reed switchover contacts with such a transition are known per se. T-hese known contacts are based on the conventional principle in which a magnetizable switchover contact spring is arranged between a nonamagnetizable break-contact piece and a magnetizable make-contact piece. Normally lthe switch-over contact spring rests on 'the break-,contact piece. When such 4a contact is placed -in a magnetic Ifield, .attraction powers occur between the magnetizable switch-over spring Contact and the magnetizable make-.contact piece. This causes a closing of the contact lsurface between the switch-over contact spring .and the make-contact piece.

Transition fin the known reed-type, switch-over contact is obtained because an elastic piece is provided at the make-contact piece ,which is lattracted Ato the switch-over contact spring when excited by a magnetic held. The resetting force of the end-piece is less than the contactmaking force of the switch-over contact spring with which the latter rests on :the break-contact when .in the runoperated position.

The switch-over contact spring has, at its movable end, a bridge representing the `only part `of Ithe switch-over contact spring 'which is magnetizable. In parallel with the switch-over contact spring is .a particularly rigid magnetic flux guide which comes close 4to the part designated as a bridge. A fter closure `of the contact between the switchover contact spring and the end ofthe 'make-.contact piece, a magnetic flux occurs between the bridge and the magnetic iiux 4guide :for attracting the bridge while the end of the make-contact clings to the bridge. The contact is interrupted at the break-contact `only after the making of the make-contact.

This arrangement described above is a construction completely different `from .the conventional reed contacts construction. Particularly reed lswitch-over contacts, of conventional design, require a special production technique due to their plurality yor parts. `For example, a known magnet-operated reed-typeswitch-over contact with transition consists of :two blades, which in normal position rest on the break-contact. One blade is designed in such a way that it needs less excitation than the other one and which moves only when the reed is nearly Ifully magnetized. This arrangement, however, has the disadvantage that the pull-up and dropping values result solely 'from the different lengths of ,the individual springs separated by 'a slot. These values are not high enough to manufacture a properly working reed switch-over contact with transition.

An 'object of the invention is to -create a reed switchover contact with transition which can easily be produced and which operates with distinctly .dened pull-up and dropping values. This is achieved by providing the known, slotted switch-over contact blade with both magnetic ma-terial and non-magnetic material. In Ithe normal position of Ithe slotted switch-over contact blade, on the breakcontact spring of non-magnetic material, one blade half rests with the magnetic part of its contacts on the brealc contact spring and the other blade half rests with its nonm-agnetic part on rthe break contact spring.

Due to arrangement, the response and dropping values are exactly delined with `a result such that the reed contacts with blades slotted into halves, more responsive to excitation by va magnetic iield. One blade half with a smaller magnetic gap lirst moves towards a make-contact spring consisting of non-magnetic material where it makes an electrical contact. The other blade half with a larger magnetic gap still touches the break-contact. It is lifted from there yonly when the excitation increases, and then it contacts the make-contact spring. For dropping, exactly the same defined values apply without reversing the switch-over sequence lof the individual contact blade halves.

The invention is now described with the aid of ra drawinginwhich:

FIG. 1 shows .a part of a reed switch-over contact, enlarged in scale and in operating position,

FIG. 2 (a to e) shows a section through the contacts of the reed switch according to FIG. l, representing the different contact positions during operation, enlarged scale, land FIG. 3 (a to e) shows a section through the contacts of another switch-over contact in which only one blade half is provided on either side alternately with a precious metal coating, representing the diierent cont-act positions during operation, enlarged scale.

In FIG. l Ia glass-sealed part of the reed contact is marked `1. A break-contact spring '2 olf non-magnetic material and a make-contact spring 3 of magnetic material is provided. On the opposite 'Pfront side of 1 a switch-over con-tact spring 4 Voi" magnetic material is mounted. The switch-over contact spring is positioned between the inner surfaces of contact springs 2 and 3, and rests on nonopera'tive condition with its two blade halves l5 and `6 separated by a slot, on the break-contact 2. Both blade halves l5 and 6 are provided with non-magnetic material along the entire length of the slot, e.-g., a contact material such as gold, silver and the like. The precious metal coating is applied -in such a way, when the switch-over cont-act blade 4 is in the rest-ing position on the breakcontact spring 2, one blade hal-f 5 rests with its magnetic part on the break-contact spring 2 and the contact surface with the non-magnetic precious-metal coating 7 ypoints towards the make-'contact spring 3. The other blade ha'l'f l6 rests with its non-magnetic precious-metal coating 8 on the break-contact spring 2, and the Contact surface of magnetic material points towards the make-contact spring 3. In FIG. 1 the moment of operation is represented in which one blade half 5 still rests on the breakcon-tact 2 while the other blade half A6 already contacts the make-contact '3.

FIG. 2 shows the position of the different contacts during their operation. They can be operated either by a variable magnetic iield, e.g. a coil, or by a permanent magnet moved towards and away from the reed contact. Position a shows the unoperated position of the contacts. In this position the blade half 5 rests with its magnetic part on the break-contact 2 while the nonmagnetic, precious-metal coated part 7 points towards the make-contact 3. The other blade half rests with its precious-metal part 8 on the break-contact 2, while the magne-tic-material part points towards the makecontact 3. FIG. 2b shows how, at reaching a certain magnetic circulation, the blade half 6, having a smaller gap with respect to the make-contact 3, is moved towards the make-contact 3. An electrical connection is made at 6, 3 while blade half 5 is still resting on the breakcontact 2. When the excitation increases, FIG. 2c, blade half 5 follows half 6, interrupting its connection with the break-contact 2. If the excitation drops by a defined value the blade half parts from the make-k co'ntact 3, because the precious-metal coating 7 on the blade half 5 acts like a separating strip. This establishes a contact with the break-contact 2 while the blade half 6 still sticks to the make-contact 3 due to the force of the magnetic field. If the excitation drops by another defined value, FIG. 2e, the `spring resetting force of the switch-over contact blade 4 or of the blade half 6 exceeds the remaining residual magnetic force between Contact blade 6 and the make contact 3, so that the blade half 6 returns to its resting position at the break-contact Z.

FIG. 3 shows another example for a switch-over contact with transition in which only one blade half, eg; 6

is alternately provided with a precious-metal coating.

If the bladeehalves 5 and 6 are Operated as shown in FIG. 3a to c the blade is attracted as described and shown in FIG. 2a tov c. Since, however, the bladehalf 5, consisting of magnetic material rests without preciousmetal coating on the contact blade 3 the contact sequence is reversed for the dropping as compared with that of the pulling up, because an adhesive force exists between the blade half 5 and the make-contact 3.

The precious-metal coating can for both examples be Y first and'second spaced apart stationary contacts; Y

a bifurcated movable contact having tirst l'and second blades; v

said iirst and second blades being mounted to move independently between the first and second stationary contacts and being vnormally biased so that said blades rest in contact with said first stationary Vcon-y tact; Y Y g said first blade including a magnetic part for contacting said iirst stationary contact;

said second blade including a irst part made of conductive material to contact said iirst stationary con tact and a 4second part made of magnetic material substantially coextensive kto and in Contact with said rst part, .to` Contact -said second stationary contact; said magnetic part of saidvsecond blade being spaced closer to said second stationary contact than theV magnetic part of said first blade; said relative rspacing of the respective magnetic parts of said blades from said second stationary contact p determining the order in which said'blades will shift from contact with one stationary contact to the other in response to changing magnetic forces.

References Cited bythe Examiner UNITED STATES PATENTS 2,397,123 3/46 Brown i--- 200-87 3,068,335 12/62 Gregg 200466 FOREIGN PATENTS 1,110,308 7/61 Germany.

BERNARD K. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

